The use of radars in automotive applications is evolving rapidly. Radar finds use in number of applications associated with a vehicle such as collision warning, blind spot warning, lane change assist, parking assist and rear collision warning. Pulse radar and FMCW (Frequency Modulated Continuous Wave) radar are predominately used in such applications.
In an FMCW radar, a local oscillator generates a frequency ramp segment by frequency modulating a transmit signal. The frequency ramp segment is also referred as a chirp. The frequency ramp segment is amplified and emitted by one or more transmit units. The frequency ramp segment is scattered by one or more obstacles to generate a scattered signal. The scattered signal is received by one or more receive units in the FMCW radar. A signal obtained by mixing the frequency ramp segment and the scattered signal is termed as an IF (intermediate frequency) signal. The frequency (f) of the IF signal is proportional to the distance (d) of the obstacle from the FMCW radar and also to the slope (S) of the frequency ramp segment.
The IF signal is sampled by an ADC (analog to digital converter). A sampled data generated by the ADC is processed by a processor to obtain a position and a velocity of the one or more obstacles. In one kind of FMCW radar, the processor performs FFT (fast fourier transform) based coherent processing on the sampled data. However, this conventional processing requires a large amount of memory in the processor. This adversely affects a size of the FMCW radar.
Some of the existing FMCW radars use known memory compression techniques to compress the data generated in FFT processing. However, these memory compression techniques are lossy in nature thereby resulting in degradation of an accuracy of the radar system. Another conventional approach of memory reduction is based on limiting a range of the FMCW radar that can be viewed in a single frame of FFT processing. Thus, multiple frames are transmitted by the transmit unit, and each frame is dedicated to a specific range. In this approach, since multiple frames are required for single viewing, it increases a power consumption of the FMCW radar, and also makes it difficult to use the FMCW radar in real time applications.